A work machine, such as an agricultural tractor, typically includes a coupling arrangement (sometimes referred to as a 3-point hitch) for attaching a work implement to the work machine. The coupling arrangement generally includes a link assembly for connecting an arm and a bar which extend outwardly from the frame of the work machine.
The link assembly includes an internally threaded sleeve and an externally threaded rod positioned within the internally threaded sleeve. The externally threaded rod meshingly engages the internally threaded sleeve so that relative rotation between these two elements in a first direction causes the externally threaded rod to be advanced out of the internally threaded sleeve thereby increasing the length of the link assembly. In the alternative, relative rotation between these two elements in a second direction causes the externally threaded rod to be advanced further into the internally threaded sleeve thereby decreasing the length of the link assembly. Adjusting the length of the link assembly in the above described manner is important for ensuring that the work implement is appropriately attached to the work machine.
Heretofore, various devices have been utilized to accomplish the above described relative rotation between the internally threaded sleeve and the externally threaded rod. For example, a wrench can be used to accomplish the rotation. However, utilizing a separate tool such as a wrench is inconvenient for the operator of the work machine since he or she must constantly carry the tool with them in order to make the appropriate adjustments to the length of the link assembly.
In addition, a separate tool such as a wrench does not address the problem of the length of the link assembly inadvertently changing during the use of the work machine. In particular, vibrations generated during use of the work machine are communicated to the internally threaded sleeve and the externally threaded rod through various work machine structures. These vibrations can cause relative rotation between the internally threaded sleeve and the externally threaded rod. As a result, the length of the link assembly inadvertently changes during use of the work machine which can adversely effect the performance of a work function.
In an attempt to address the aforementioned problem, some coupling arrangements include a latch for preventing the relative rotation between the internally threaded sleeve and the externally threaded rod. Some of these latches are designed so that when they are unlatched they can function as a handle which is attached to the internally threaded sleeve or the externally threaded rod. This handle is grasp and rotated by the operator of the work machine so as to cause relative rotation between these elements and thereby change the length of the link assembly.
However, a drawback to these types of latches is that they are permanently attached (e.g. pinned) to the link assembly Having the latch permanently attached to the link assembly significantly decreases the flexibility with which the latch can be positioned during the time it is used as a handle to accomplish above described relative rotation. As a result, these types of latches are difficult to use and decrease the efficiency with which an operator can adjust the length of the link assembly.
What is needed therefore is a coupling arrangement which overcomes one or more of the above-mentioned drawbacks.